1. Field of the Invention
This invention relates to heat exchangers and more particularly, to truck and industrial heat exchangers.
2. Description of Related Art
Heat exchangers or radiators utilized in heavy trucks and some industrial applications are typically comprised of cores fabricated from three (3) or four (4) rows of oval shaped solder-coated brass tubes in a heat exchange relationship with corresponding louvered serpentine copper heat transfer fins. A heat exchanger comprising three (3) rows of heat exchanger tubes is known as the 3R VTD core, and a heat exchanger comprising four (4) rows of heat exchanger tubes is known as the 4R VTD core. The maximum fin count in these cores is about 16 fins per inch. Typically, the tubes are separated, in the direction of air flow, by a space of about 0.155 inch. However, it has been found that these spaces between the tubes do not transfer heat and thus, impede the cooling process of the hot fluid flowing through the tubes. Thus, these spaces are essentially wasted. It has also been found that the flat non-louvered portions of the copper fins, between the louver banks, are not as efficient as the louvered portions in effecting transfer of heat from the tubes.
FIG. 2a shows a conventional core layout 20 which is known as the 4R VTD heat exchanger. The 4R VTD core 20 is comprised of four (4) rows of heat exchanger tubes 12. The heat exchanger has a core depth W.sub.A of approximately 3.04 inches, a tube centerline spacing S.sub.A of approximately 0.57 inch and a space F.sub.R of approximately 0.155 inch between each heat exchanger tube 12 (in the direction of air flow). The spaces F.sub.R between the heat exchanger tubes do not effectively transfer heat and thus, are essentially wasted. FIG. 2b shows the dimensions of the oval heat exchanger tube utilized in the 4R VTD design of FIG. 2a. The major and minor diameters A.sub.R and C.sub.R, respectively, of tube 12 are approximately 0.625 inch and 0.078 inch, respectively. The ratio of major diameter to minor diameter is approximately 8 to 1 (8/1). The tube wall thickness T.sub.R is approximately 0.008 inches. The hydraulic diameter of tube 12 is about 0.1145 inch.
FIG. 3a shows another conventional core layout which is known as a 3R VTD heat exchanger 22. The 3R VTD heat exchanger is comprised of three (3) rows of heat exchanger tubes 12. The heat exchanger has a core depth W.sub.B of approximately 2.29 inches, a tube centerline spacing S.sub.B of approximately 0.57 inch and a space F.sub.R (in the direction of air flow) of approximately 0.155 inch between heat exchanger tubes 12. Similar to the 4R VTD design, the spaces F.sub.R between heat exchanger tubes 12 of the 3R VTD core 22 do not effectively transfer heat and thus, are essentially wasted spaces. FIG. 3b shows the dimensions of the oval heat exchanger tubes utilized in the 3R VTD design. The major and minor diameters A.sub.R and C.sub.R, respectively, of the heat exchanger tubes 12 are approximately 0.625 inches and 0.078 inches, respectively. The ratio of major diameter to minor diameter is approximately 8 to 1 (8/1), which is the same as in the 4R VTD design. The tube wall thickness T.sub.R is approximately 0.008 inches, which is also the same as the 4R VTD design. The hydraulic diameter of tube 12 in the 3R VTD core is 0.1145 inch, which is the same as in the 4R VTD core.
FIG. 5a shows another conventional core layout 28 which is known as the 2R VTD heat exchanger. The 2R VTD core 28 is comprised of two (2) rows of heat exchanger tube 12. The 2R VTD core 28 has a core depth W.sub.D of approximately 1.54 inch, a tube centerline spacing S.sub.D of approximately 0.57 inch and a space F.sub.R of approximately 0.155 inch between tubes 12. As found with the 3R VTD and 4R VTD core layouts, the 0.155 inch space between tubes 12 in the 2R VTD core does not effectively transfer heat and basically amounts to wasted space. FIG. 5b shows the heat exchanger tube 12 utilized in the 2R VTD core. This tube has dimensions that are the same as those of the tubes utilized in the 3R VTD and 4R VTD cores and thus, has the same 8 to 1 (8/1) major diameter to minor diameter ratio.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a new and improved heat exchanger that minimizes or eliminates wasted space between heat exchanger tubes in the direction of air flow, thereby facilitating efficient transfer of heat from the tubes.
It is a further object of the present invention to provide a new and improved heat exchanger that utilizes fewer heat exchanger tubes and heat transfer fins than conventional designs.
It is yet another object of the present invention to provide a new and improved heat exchanger that is smaller in size than the aforementioned conventional heat exchangers but yet, has the ability to cool larger engines.
It is a further object of the present invention to provide a new and improved heat exchanger that is of simple construction and light weight.
It is a further object of the present invention to provide a new and improved heat exchanger that allows vehicle manufacturers to improve vehicle aerodynamics.
It is another object of the present invention to provide a new and improved heat exchanger core that has a core face surface area that is less than that of the aforementioned conventional heat exchangers without sacrificing heat transfer efficiency.
It is another object of the present invention to provide a new and improved heat exchanger that has a core airside pressure drop that is approximately the same as that of the aforementioned conventional heat exchangers.
It is another object of the present invention to provide a heat exchanger that can be manufactured at a reasonable cost.